Structure and function of yeast Lso2 and human CCDC124 bound to hibernating ribosomes

PLoS Biol. 2020 Jul 20;18(7):e3000780. doi: 10.1371/journal.pbio.3000780. eCollection 2020 Jul.

Abstract

Cells adjust to nutrient deprivation by reversible translational shutdown. This is accompanied by maintaining inactive ribosomes in a hibernation state, in which they are bound by proteins with inhibitory and protective functions. In eukaryotes, such a function was attributed to suppressor of target of Myb protein 1 (Stm1; SERPINE1 mRNA-binding protein 1 [SERBP1] in mammals), and recently, late-annotated short open reading frame 2 (Lso2; coiled-coil domain containing short open reading frame 124 [CCDC124] in mammals) was found to be involved in translational recovery after starvation from stationary phase. Here, we present cryo-electron microscopy (cryo-EM) structures of translationally inactive yeast and human ribosomes. We found Lso2/CCDC124 accumulating on idle ribosomes in the nonrotated state, in contrast to Stm1/SERBP1-bound ribosomes, which display a rotated state. Lso2/CCDC124 bridges the decoding sites of the small with the GTPase activating center (GAC) of the large subunit. This position allows accommodation of the duplication of multilocus region 34 protein (Dom34)-dependent ribosome recycling system, which splits Lso2-containing, but not Stm1-containing, ribosomes. We propose a model in which Lso2 facilitates rapid translation reactivation by stabilizing the recycling-competent state of inactive ribosomes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism
  • Amino Acid Sequence
  • Binding Sites
  • Cell Cycle Proteins / chemistry*
  • Cell Cycle Proteins / metabolism*
  • Conserved Sequence
  • Evolution, Molecular
  • HEK293 Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins / chemistry*
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Models, Molecular
  • Peptides / chemistry
  • Protein Binding
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Transfer / metabolism
  • RNA-Binding Proteins / metabolism
  • Ribosomal Proteins / chemistry*
  • Ribosomal Proteins / metabolism*
  • Ribosomes / metabolism*
  • Ribosomes / ultrastructure
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae / ultrastructure
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Structure-Activity Relationship

Substances

  • Adaptor Proteins, Signal Transducing
  • Ccdc124 protein, human
  • Cell Cycle Proteins
  • Intracellular Signaling Peptides and Proteins
  • LSO2 protein, S cerevisiae
  • PA2G4 protein, human
  • Peptides
  • RNA, Messenger
  • RNA-Binding Proteins
  • Ribosomal Proteins
  • Saccharomyces cerevisiae Proteins
  • RNA, Transfer